@Ben, the thing with most of the fuses sold on the UK market is that the brands make no provable claims for them in the marketing. For example, all electrical devices work on the quantum level, anything involving electrons is essentially 'quantum'. And the claims extend no further that parroting customer feedback of improved sound, which are already proven by the customer providing their opinion. They aren't making any claims that are verifiable through other means.
If you find one that is making such claims hit the ASA up, they have budget to go after them.
I've twice submitted reports, one for russ Andrews and his sawyers discs, a well known case, which was upheld and forced him to change the ads and another for a speaker company from Brighton which was similarly ordered to change their ads.
It's worth doing.